已知向量$\overrightarrow{AB}$与$\overrightarrow{AC}$的夹角为${120}^{\circ }$,且$\left|\overrightarrow{AB}\right|=2,\left|\overrightarrow{AC}\right|=3$,若$\overrightarrow{AP}=\lambda \overrightarrow{AB}+\overrightarrow{AC}$,且$\overrightarrow{AP}\perp \overrightarrow{BC}$,则实数$\lambda$的值为(   ）

    Breakfast is very important. It is one of the most important1of the day. To keep healthy, everyone should2a good breakfast.3the right food is necessary for good health. We may have eggs, bread, milk and so on,4breakfast. Many students go to school without breakfast5they get up late or their parents don't cook for them. It's6for their health.7breakfast children may not grow fast and may not study and play very well at school. They may8. And when they're ill, they will9a long time in recovering (恢复). I think everyone should have some good10habits. It is necessary.

读图1和图2，回答下列问题。

①三边对应成比例的两个三角形相似;

②一个角对应相等的两个直角三角形相似;

③一个锐角对应相等的两个直角三角形相似;

④一个角对应相等的两个等腰三角形相似.

其中正确的命题是（  ）